18.9 Study on Service continuity between mobile and wlan networks uid_340035

Resources: S1

References

Document	Title/Contents
WID(s)
SP-060936	SID on Requirements for seamless roaming and service continuity between mobile and WLAN networks
Impacted Specifications
-	-
New Dedicated Specifications/Reports
TR 22.937	Requirements for service continuity between mobile and Wireless Local Area Network (WLAN) networks

Supporting Individual Members: BT, AT&T, Huawei, Giesecke & Devrient, Gemalto.

For Fixed-Mobile Convergence (FMC), some scenarios require seamless roaming between GSM/GPRS/3G mobile and WLAN networks. Both networks may independently be authenticated. To maintain the quality of the customer experience, and due to the difference of networks, handovers to support service continuity may require that the handset is authenticated to both networks simultaneously, for relatively short periods of time.

One use case is where the user, on the way to office, is having a call on a 3GPP access network using the mobile phone. Roaming onto the office WLAN (and vice versa), while still being on the line and the call is transferred without the user noticing any interruption to the network served by the WLAN..

The study proposes requirements while roaming between a GSM/GPRS/3G mobile network and a WLAN network for:

• seamless roaming and service continuity;

• maintaining service quality and service continuity;

• charging;

• security, in particular when networks may be independently authenticated.

TR 22.937 develops use cases and requirements for service continuity between a 3GPP network and another network, which can be:

• a TISPAN NGN with an IMS, accessed by a WLAN;

• an ISP accessed via a WLAN.

Each access network has its own separate security system and the network operators have a commercial agreement for roaming and handover.

TR 22.937 Recommendations

General recommendations

• to reuse the mechanisms already defined in 3GPP specifications and the roaming mechanisms.

• to use the flexibility already defined in 3GPP specification, such as taking benefit from the possibility to establish multiple ISIM (IM Services Identity Module) on the UICC when multiple IMS subscriptions are needed.

Proposed requirements

Security aspects

• It shall be possible for the 3GPP Network Operator (NO) and the WLAN NO to operate their own completely separate security systems, including independent authentication centres in their respective CNs.

• UE shall be capable of connecting to the non-3GPP network via a WLAN in a secure way using the appropriate security and authentication mechanisms for that network.

• UICC shall be able to support separate NAAs for the 3GPP access and WLAN access, where the credentials in each NAA are different.

• Where the UICC supports separate NAAs (Network Access Applications on the UICC) for 3GPP access and WLAN access, the UICC shall permit simultaneous sessions with both NAAs on different logical channels.

• In case the PNO (Primary Network Operator; a non-3GPP operator with WLAN coverage) has a commercial roaming agreement with the SNO (Secondary Network Operator; a 3GPP operator) that allows PNO users to roam into SNO mobile network, the already defined I-WLAN specification TS 22.234 allows to re-use USIM authentication and network selection mechanism.

• UE shall be capable of connecting to the 3GPP network via a WLAN in a secure way using I-WLAN security and authentication mechanisms for that network as defined in TS 22.234.

• UE shall support already defined security and authentication requirements to connect to the 3GPP network (e.g. USIM-AKA, SIM-AKA) or to the 3GPP IMS domain (e.g. IMS-AKA, HTTP digest).

AKA Authentication and Key Agreement

NOTE: The WLAN network could be considered an IP-CAN when used to access the IMS domain

Service aspects

• It shall be possible to support service continuity of the multimedia session, including the IMS session, if used, from the WLAN to the 3GPP network and vice-versa.

• The system shall be capable of assuring service continuity to the end user, when moving between WLAN access network and the 3GPP access network.

• In the case service continuity is required, there is a work in Rel-8 to define multimedia sessions continuity.

• UE shall be capable of providing information to the user regarding the current type of access used.

• The ability to maintain service continuity when changing networks shall be dependent on the QoS capabilities of the target network.

• It shall be possible for the PNO to reject the change of network if the target network does not provide adequate QoS to maintain service continuity.

• It shall be possible to release the session on change of network if the target network does not provide adequate QoS.

• The system may adapt the service (e.g. degrade or enhance the service) to the capability of the target access.

Charging aspects

• NO shall be aware of the status of the UE with respect to the network attachment and shall be capable of charging the subscriber according to the type of access used.

• NO shall be capable of collecting on-line and off-line charging information.